Susilo Widodo

Single-particle strengths measured with 48Ca(d, p)49Ca reaction at 56 MeV

Single-particle states in 49Ca have been investigated through the 48Ca(d, p)49Ca reaction initiated by vector-polarized deuterons of Ed = 56 MeV. Thirty-six levels were observed up to 8 MeV excitations. Transferred l, j values were deduced for these levels by measured angular distributions of cross section and analyzing power. We observed many additional states and corrected some previous jπ assignments. The total values of spectroscopic factors C2S obtained with zero-range distorted-wave-Born-approximation (DWBA) calculations are almost unity for the shells 2p32, 2p12 and 1f52, and no 1f72 states are observed. It is confirmed that 48Ca has a good closed-shell structure, the feature of which is consistent with occupation probabilities predicted from an extended second RPA theory.

Hole strengths and spreading widths observed in 92Mo(p, d)91Mo reaction at 65 Me V

Abstract Differential cross sections and analyzing powers have been measured for the 92 Mo ( p , d ) 91 Mo reaction with a polarized proton beam of 65 MeV incident energy for investigating the level structure of 91Mo up to 10 MeV. The data analysis with the standard DWBA theory provides transferred angular momenta lj values and spectroscopic factors for 42 transitions to the single-hole 1 g 9 2 , 2 p 1 2 , 2 p 3 2 , 1 f 5 2 and 1 f 7 2 st analog states. The spreading widths are deduced and compared with theoretical predictions for discussing the damping mechanism of the single-hole states.

A self-quenched streamer tube operated with Ne- and He-mixtures

Abstract Gas-multiplication properties have been studied for several Ne- and He-mixtures to discuss the self-quenched streamer (SQS) transition, and compared with those for Ar-, Kr- and Xe-mixtures. The SQS tube operated with a NeisoC4H10 mixture shows good performance as a radiation-monitoring device.

Generation of SQS in quenching gas (CH/sub 4/) of proportional counter and related problems

Two topics concerning the self-quenching streamer (SQS) phenomenon in proportional counters are reported. One is the observation of the SQS transition in pure methane gas under irradiation with 4.5-kV X-rays. The effect of a small amount of argon on the SQS transition was investigated with gas mixtures (CH/sub 4/ 4:Ar) having mixing ratios of 100:0, 99.8:0.2, 99.7.03, 99.5:0.5, 99:1, 98:2, 95.5:0.5, and 90:10. A SQS transition was not observed in pure methane gas, although it was observed in the gas mixture of 99.8:0.2. The other topic discussed is the measurement of electron drift characteristics with a single-wire gas counter operated in the SQS transition regions. The counter gas used was a mixture of argon and methane (70:30) to which ethanol vapor was added. From comparison with the proportional mode, the use of the SQS mode is recommended to obtain a better time resolution in the application of the drift counter.<<ETX>>

Position sensing with Ne-based gases in the SQS transition region

Abstract The characteristics of Ne-based gases for position sensing have been investigated in the self-quenching streamer (SQS) transition region, using a single wire proportional counter with cathode strips. As the quenching gas we used CH 4 with some mixing proportions. Position sensing was performed by the charge division method with a ratio-to-digital converter (RDC). With CH 4 of more than 30% in concentration, the SQS transition appears clearly and the addition of C 2 H 5 OH makes the operation quite stable. It is impossible to detect X-rays with freon additive gases, i.e., a Ne-based magic gas mixture, probably due to a too strong electron attachment in this mixture.

Electron drift measurements using self-quenching streamer mode in single wire gas counter

The behavior of the SQS (self-quenching streamer) discharge induced by beta -rays in a single wire gas counter was studied, and its applicability to measurements of electron drift has been clarified. It was possible to use the SQS signal from beta -ray induced ionization instead of the SQS signal from laser-induced ionization for electron drift measurements. This method is very simple and gives drift velocity data in a wide range of electric field strength, especially at high regions where a uniform field drift counter is not so easy to operate. Ne-based gas mixtures show less saturation of drift velocity than Ar-based gas mixtures for the electric field regions commonly applied for drift counters.<<ETX>>

Polarized Proton Induced Breakup of 12C at 14 and 16 MeV

Double differential cross sections and analyzing powers are measured of protons and α particles emitted from the bombardment of 12C with 14 and 16 MeV polarized protons. The measured energy spectra of protons and α particles are analyzed on the basis of the reaction model in which three or four-body simultaneous breakup process is taken into account. The calculated proton and α spectra show good agreement with the continuous spectra observed in the low outgoing energy range.